Current chipsealing processes involve applying a film of rapid setting asphalt emulsion to a roadway surface to seal cracks and imperfections. This is followed by applying a single layer of aggregate onto the emulsion to provide a riding surface. Typically, extra aggregate is not swept away immediately but remains on the road for at least one night to allow sufficient time for the bitumen to harden. Traffic is released to the new surface before the excess aggregate is swept away thus creating a high potential for vehicles being damaged from the loose aggregate.
Typical chipseal formulations utilized today include blends of tallow polyamines as emulsifiers. A major component of the blend is usually a tallow diamine. Typically, hydrochloric acid is added to the emulsifier to form a hydrochloride salt.
U.S. Pat. No. 4,576,648 (the '648 patent) suggests the use of cationic emulsifiers and a carboxylic acid. More specifically, the '648 patent discusses imidazoles and other cationic nitrogenous compounds as valuable to improving the long-term aging properties of a bituminous emulsion after the emulsion has broken. This is evidenced by the '648 patent's discussion of improving the aging properties of the binder and verifying this using an artificial aging Rolling Thin Film Oven test (RTFO test), which causes the emulsion being tested to break. The '648 patent provides no suggestion as to how to optimize the formulation of a bituminous emulsion to improve its short-term properties, such as coalescence. In fact, the '648 patent teaches away from the present invention by stating that aliphatic amines or fatty amines are particularly suitable cationic emulsifying agents.
In order to overcome the disadvantages of current paving processes, a method of selecting a better bituminous emulsion for a paving process is provided. This method includes performance testing a bituminous emulsion before selecting it for a paving process.